Combination ladder



Jan. 14, 1969 KOlCHl YOSHIHISA 3,421,593

COMBINATION LADDER Filed Oct. 11, 1966 Sheet or 5 u or 9 R239 m l rrr' 1 n e KOICHI YOSHIHISA COMBINATION LADDER Jan. 14, 1969 5118?; 2 ors Filed Oct. 11, 1966 1969 KOICHI YosHu-n'sA COMBINATION LADDER Sheet 3 ors Filed Oct. 11, 1966 United States Patent 3,421,598 COMBINATION LADDER Koichi Yoshihisa, Osaka, Japan, assignor to Showa Aluminum Kabushiki Kaisha, Osaka, Japan, a corporation of Japan Filed Oct. 11, 1966, Ser. No. 585,946 US. Cl. 18224 Int. Cl. E06c 1/14 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to a combination ladder, more particularly, the combination ladder which can be used as a stepladder as well as an ordinary ladder.

In the prior art, the conventional combination ladder has been plagued with various disadvantageous features. For instance, every time in case of the changeover of the use of the conventional ladder from a stepladder to an ordinary ladder or from the ordinary ladder to the stepladder, it has required to perform troublesome operations and to use the complicated devices at the same time.

The main object of the present invention is to overcome the said defects of the conventional combination ladder by providing a new combination ladder, the changeover operations of which as above-mentioned are very simplified.

Another object is to provide the combination ladder having a simplified changeover device between the stepladder and the ordinary ladder and a good form at the same time.

A further object is to attain the combination ladder, the safe and efficient operation of which is always ensured whenever it is used as a stepladder or an ordinary ladder.

A still further object of the invention is to provide the combination ladder which can be easily folded up and is so light as to be conveniently carried anywhere required.

These and other objects of the invention are attained in a specific illustrative embodiment thereof which briefly comprises a first step member having spaced side legs with rungs extending between the side legs and supported thereby a second step member which is substantially the same as the first step member, a hinge which is arranged astride of the first and second step members at one end of their respective side legs, the lock means having the operation lever which fixes said hinge so as to maintain the first and second step members on a straight line, a connecting rod which maintains the first and second step members in a reversed V-shape and the bench fixed upon the said connecting rod.

Other features, objects and advantages of the present invention will be apparent as the detailed description proceeds and upon reference to the accompanying drawings in which:

FIG. 1 is the partly broken side view of the embodiment of the invention illustrating the combination ladder used as the stepladder and folded up in a reverse V-shape.

3,421,598 Patented Jan. 14, 1969 FIG. 2 is a elevational view of the embodiment of FIG. 1.

FIG. 3 is a enlarged sectional view taken along section line 3-3 of FIG. 1.

FIG. 4 is a partly enlarged perspective view of the lower part of the step member.

FIG. 5 is a side view of the embodiment of the invention elongated in a straight line as used for an ordinary ladder.

FIG. 6 is an enlarged side view of the hinge and the lock means, showing the locked position of the ladder.

FIG. 7 is an elevational view of the hinge and the lock means which are shown in FIG. 6.

FIG. 8 is a sectional view taken along section line 88 of FIG. 6.

In FIGS. 1-5, the preferred embodiment of the combination ladder according to the invention are shown, where the said ladder is used as the stepladder as well as the ordinary ladder. It comprises the first step member 1 and the second step member 2, both of which are substantially the same, having two separate side legs 3, between which are arranged the separately elongate rungs 4 and 5 that are in parallel with each other. The side legs 3 are of the extrusion of aluminum or aluminum alloy. Its cross section has a U-shape and its groove 6 is facing inside. Likewise the rungs 4 and 5 are of the extrusion of aluminum or aluminum alloy. As shown in FIG. 4, the rung 4 is formed to have a hollow rectangular section and, on its upper and lower sides, it is equipped with several non-slip springs 7. On both left and right ends of the rung 4, it has the elongate angular flange 8 that is folded upward and downward. The angular flange 8 is put on the inside plane of the side leg 3 to be fastened thereto by the rivet 9. In order to specially reinforce the lowest rung 4, the oblique bracket 10 is arranged from its lower side of both left and right over the inner side of the respective side leg 3 to be fastened by the rivet 11. As shown in FIGURES l and 3, the rung 5 is a round hollow pipe and its both ends are put in and fastened to the adapter plate 12 which is of a longitudinally rectangular shape and has a fitting hole in its center to be fastened by the rivet 13 to the inner side of the side leg 3 near its end.

To the rung 5 of the second step member 2 in the neighborhood of its both ends is rotational-1y fastened the angular base 14b of the connecting rod 14 which has become a hook 14a in its end. In other words, the rung 5 of the second step member 2 is so made as to be the axis of the rotary connection rod 14, while the hook 14a at the tip of the connection rod 14 is fastened to the rung 5 of the first step member 1 i.e., the rung 5 forms a bar for hooking the said rod 14. Upon the two connection rods 14 and 14 are put the square-shaped work bench 15 to be fastened thereto by the rivet 16, so that it may move together with the connection rod 14. The brim 15a which comes out slightly downward is arranged around the said work bench 15, and the oblong notch 17 is formed, in order to pull the sledge 5 out of the hook 14a of the connection rod 14, at the point where the said brim 15a crosses the rung 5 of the first step member 1.

To the base end of the respective side leg 3 of both the first and second step member 1 and 2 is provided a non-slip device 46 made of a plastic material such as rubber, while the inserting part 47 which agrees with the inner side of the groove 6 of the side leg 3 is provided in the non-slip device 46, while the inserting part 47 is put into the groove 6 from the end of the side leg 3 and the outside of the said inserting part 47 is covered with a square-shaped cover plate 48 to be fastened to the side leg 3 by the rivet 49. The non-slip device 46 has its bottom side 45a inclined so as to be along the ground surface when the ladder is used as a stepladder (see FIG. 1).

It is also provided with several parallel grooves 50 running in the direction of its width. Upon the one side of the non-slip device 46 is provided an arc-shaped convex part 51 which comes out sideways from the side leg 3. When the ladder is used as the ordinary one, the said convex part 51 will touch a building so that, by its elasticity, the building may be protected from being hurt by the ladder (see FIG. 5).

To the tips of the respective side legs 3 of both the first and second step members 1 and 2 are provided the hinge 18 and the lock means 19 made of aluminum or aluminum alloy. The detail of the above-mentioned construction is shown in FIGS. 68. The said hinge 18 comprises the first plate 20 fit on the tip of the respective side legs 3 of the first step member 1 and the second plate 21 at the tip of therespective side legs 3 of the second step member 2. The first plate 20 has a U-shaped base 20a in its cross section which may be used to cover the side leg 3, while its one end protrudes sideways to form a tongue part 22 and the base 20a is inserted from outside into the tip of the respective side legs 3 to be fastened by the bolt and nut 23 in its both side walls.

The second plate 21 is fastened by such a thing as a welded joint 25 to the outside of the base 24 that has a U-shaped cross section which may be used in covering the side leg 3, and at its tip is formed a covering part 45 which has its corner, on its one side covering the outside of the first plate 20, made into a curved plane 45a, while its one end is protruding sideways to form a tongue part 26 which is piling on the tongue part 22 of the first plate 20. The base 24 is inserted from outside into the tip of the respective side legs 3 to be fastened by the bolt and nut 27 on its both side walls. Both the tongue part 22 of the first plate 20 and the tongue part 26 of the second plate 24 are rotationally connected by the pivot 28, so that by the above-mentioned hinge 18 the first step member 1 and the second step member 2 are so connected with each other as to be freely folded up.

The lock means 19 comprises the hook 29 and its op-v eration lever 30. The hook 29 has the inclined head 29a the round base 31, through the center of which the pivot 32 passes to be fixed rotationally at the point separated from the tongue part 26 in the neighborhood of the one side of the first plate 20. The hook 29 is hooked to the hooking part 33 formed by cutting open the side which is opposite the tongue part 26 of the said second plate 21. On the side of the base 31 of the hook 29 is formed the notch 34, while the pin 35 which is made to stand on the outside of the first plate 20 is protruding into the notch 34. The pin 35 is made to contact the one end 34a of the notch 34 when the hook 29 remains to be hooked to the booking part 33 and, after the hook 29 is removed from the hooking part 33 until the other end 34b of the notch 34 contacts the pin 35, it can be rotated. Consequently the length of the notch 34 regulates the range of rotation of the hook 29, as easily understandable. The operation lever 30 is provided with an uprising member 36 to be handled by the operators fingers. Its round base part 37, which has a diameter smaller than that of the round base part 31 of the hook 29, is piled on the outside of the round base part 31, through the center of which the same pivot 32 passes to fix them rotationally. On the border between the said round base part 37 and the body of the operation lever 30, there are two angular members 37a and 37b, on the mutually opposite sides and, in the condition that the operation lever 30 stands side by side with the hook 29 that is then hooked, the pin 38 is erected on the outside of the round base part 31 of the hook 29 so as to contact the angular member 37a, while another pin 39 is erected on the round base part 31 which is situated in opposition to the pin 38-, holding between them the round base part 37 of the operation lever 30. The operation lever 30 can be rotated from the above-mentioned position until the angular member 37b contacts the pin 39 and pushes it, so that the pin 39 will rotate the fixed round base part 31 and its notched end 34b will contact the pin 35. Consequently it is inevitable that the range of rotation of the operation lever 30 is greater than that of the hook 29 and its angle of rotation exceeds A projection 40 is provided in the first plate 20 by cutting up its part in the neighborhood of the tongue member 22 which is on the same level as the pivot 31, but is separated therefrom, and one end of the coil spring 41 is passed through the hole 42 made by the said projection 40 and is bent to be fixed thereto, while the other end of the said coil spring 41 is passed through the hole 43 made in the uprising member 36 of the lever 30 and is likewise bent to be fixed thereto. A U-shaped cover 44 covering the most part of the abovementioned locking means 19 is, in the flange 44a provided at its one end, fixed to the outside of the first plate 20 with the screw 52.

With reference to FIG. 4, it is clear that, when the operation lever 30 is rotated counter-clockwise by the fingers on the uprising member 36, the said small spring 41 will swing with the hole 42 of the said projection 40 as its fulcrum. But, the operation lever 30 must be pulled in opposition to the spring tension until the said spring 41 will cross the line 1 which connects the projection 40 and the center of the means 32. When the spring 41 crosses the said line 1, a dead line, however, the spring tension acts so aggressively that the operation lever 30 will suddenly increase its rotation. When the spring 41 just crosses the said line 1, the angular member 37b on the border between the uprising member 36 and the round base part 37 will contact the pin 39 erected on the round base part 31 which is situated inside. But, as the tension of the spring 41 will act, the pin 39 will be pushed by the angular member 37b and the round base part 31 Will be'rotated counter-clockwise, so that the hook 29 comes olf the hooking part 33. As above-mentioned, the hook 29 will stop rotating as soon as the notched end 37b of the round base part 31 touches the pin 36. The hook 29 in the condition of being removed from the hooking part 33 and the operation lever 30 are separated from each other at an angle of 90. The releasing condition of the locking device 19 as above-mentioned is shown by a chain line in the drawing.

Likewise with reference to FIG. 4, the operation lever 30 in its condition shown by the chain line will be rotated clockwise in opposition to the tension of the spring 40, when locking the said device conversely, and for the same reason as above-mentioned, the speed of rotation of the operation lever 30 will suddenly increase as soon as it crosses the line 1, during which the angular member 37a on the opposite side of the above-mentioned angular member 37b will touch the pin 38, pushing it to make the round base part 31 rotate clockwise, so that the hook 29 may be locked to the booking part 33. Since the hook 29 is always under the influence of the tension of the spring 41 through the operation lever 30, looking is insured and remains firm.

When using the ladder as a stepladder, the locking means 19 is released in a manner as above-mentioned and the hinge 18 is set free, so that the second step member 2 will be swung toward the first step member 1 with the axis 28 as its fulcrum and the hook 14b of the connection rod 14 which is provided in the second step member 2 will be locked to the sledge 5 of the first step member 1. As a result, while the first step member 1 and the second step member 2 are maintained in the reverse V-shape as shown in FIG. 1, the work bench 15 on the upper plane of the connection rod 14 is kept up horizontally.

When carrying or housing the ladder, the hook 14b of the connection rod 14 will be removed from the rung 5 of the first step member 1, and the second step member 2 will be piled upon the first step member 1, so that the ladder may be folded in two.

When using the said ladder as an ordinary ladder, both the first step member 1 and the second step member 2 are extended in a straight line and the locking means 19 should be locked in a manner as above-mentioned. In case of using the ladder as a stepladder, both the hook 29 and the operation lever 30 are shown in FIGS. 1 and 2 in their revelled condition when releasing their locking in order to help understanding easier. Actually, however, such a condition will make trouble, if left as they are. They are therefore made to stand up in the same condition as they are locked, so that they will be locked automatically whenever they are just lined up in a straight line, because the curved plane 45a on one side of the covering member 45 of the first plate 21 will first contact the inclined plane 29a of the hook 29 to push it outwards in opposition to the tension of the spring 41, but when the covering member 45 will be piled, as predetermined, upon the outside of the first plate 20, the hook 29 will be locked automatically to the hooking part 33 on account of the tension of the spring 41. As understood clearly from the above description, the hinge 18 and the locking means 19 are cooperating to help converting the stepladder into the ordinary ladder and vice versa and that the converting operation is very simple and carried out steadfastly, insuring their safety into the bargain.

In the above-mentioned embodiment, the combination ladder is made of aluminum or aluminum alloy. But, needless to mention, any other kind of the metal or other strong materials can be used in it.

It is to be understood that the above-described embodiments are merely illustrative of an application of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. A combination ladder comprising a first step member having spaced side legs with rungs extending between the side legs and supported thereby a second step member which is substantially the same as said first step member; a hinge which is composed of a first plate that has an outwardly protruding tongue member and is fixed to the respective tips of said side legs of said first step member, a second plate which has a covering member that is piled upon a part of said first step member and is provided with a hooking part, which has a tongue member that protrudes outwardly so as to pile upon said tongue of said first step member, and which is fixed to the respective tips of said side legs of said second step member, and a pivot which rotationally connects said tongue member of said first plate and said tongue member of said second plate; a locking means which is composed of a hook that is fixed to a pivot near One side opposite to said tongue member of said first plate so as to restrictively rotate and that is fixed to said covering member of said second plate to be locked to said hooking part, an operation lever that is fixed coaxially with said hook to rotate restrictively, an interlocking mechanism that will make the rotation of said operation lever cause to rotate said hook, and a tensional spring that is fixed to said operation lever in order to maintain the locked or unlocked condition of said hook; a connection rod which maintains said first step member and said second step member in a reverse V-shape; and a work bench fixed on said connection rod.

2. A combination ladder according to claim 1 wherein a round base which has on its round brim a notch into which a pin that is erected on the outside of said first plate is protruding, is provided on said hook and, on said operation lever that has said tensional spring, a round base having a diameter smaller than that of said round base of said hook is provided, while a pair of pins are erected oppositely on said round base of said hook, holding said round base of said operation lever between them, and on the border between the body of said operation lever and said round base, two angular members are oppositely provided, and, when said operation lever stands side by side with said hook that is locked to said hooking part, said pin of said first plate contacts one end of said notch, while one of two pins of said round base is made to touch one of said two angular members.

3. A combination ladder according to claim 2, wherein said tensional spring is set up between a point near said base of said operation lever and a projection that is provided to said first plate on the same level as said pivot which is rotationally fixing said hook and said operation lever to said first plate.

4. A combination ladder according to claim 1, wherein a corner, which is on the side where there is the hooking part of a part of said covering member of said first plate, is made a curved plane.

5. A combination ladder according to claim 1, wherein there are two connection rods, one end of which is respectively fixed rotationally to a point which is near the end of the uppermost rung of said second step member, while the other end is made respectively into a hook member which is locked to a point that is near the end of the uppermost rung of said first step member and a work bench is fixed to said two connection rods to be lying across them.

6. A combination ladder comprising 'a first step member having spaced side legs with rungs extending between the side legs and supported thereby; a second step member which is substantially the same as said first step member; a hinge which is composed of said first plate that has an outwardly protruding tongue member and is fixed to the respective ends of said side legs of said first step member, a second plate which has a covering member, that is piling on a part of said first step member and is provided with a hooking part, and an outwardly protruding tongue member, that is piling upon said tongue member of said first step member, and which is fixed to respective tips of said side legs of said second step member, and a pivot which rotationally connects said tongue member of said first plate and said tongue member of said second plate; locking means which is composed of a hook that is rotationally fixed with a pivot a point near one side opposite to said tongue member of said first plate and that is locked to said hooking part provided in said covering member of said second plate an operation lever that is rotationally fixed to be coaxial with said hook, and a tensional spring fixed to said operation lever; a connection rod that maintains said first step member and said second step member in a reverse V-shape; a work bench fixed on said connection rod; and a non-slip arranged on the respective base ends of said side legs, and wherein a round base, that has on its round brim a notch into which is protruding a pin that is erected on the outside of said first plate, is provided on said hook, while said round base having a diameter smaller than that of said round base of said hook is provided on said operation lever that has said tensional spring, and a pair of oppositely standing pins are erected on the round base of said hook, holding between them said round base of said operation lever, while two angular members are oppositely provided on the border between the body of said operation lever and said base and, when said operation lever remains side by side with said hook that is locked to said hooking part,

said pin contacts one end of said notch so as to make one of two pins of said round base touch one of said two angular members, while said tensional spring is set up between -a point near said base of said operation lever and a projection provided on said first plate on the same level as said pivot that keeps rotationally said hook and said operation lever to said first plate.

References Cited UNITED STATES PATENTS 1,587,383 6/1926 Kennett l82-24 2,299,584 10/ 1942 Low 18224 3,005,513 10/1961 Larson 182-108 REINALDO P. MACHADO, Primary Examiner.

UISI Cl- X-Rn 

